Anti-blight Gene Cloned For Tomato

November 26, 1993|By New York Times News Service.

NEW YORK — Using a technology developed for the Human Genome Project, scientists at Cornell University have for the first time isolated and cloned a gene responsible for disease resistance in a major crop, tomatoes.

Transferring the gene into susceptible tomato plants through genetic engineering gave them the same protection possessed by naturally resistant plants.

The discovery, being reported Friday in the journal Science, points the way to the identification of genetic bases for many desirable agricultural characteristics, including yield, nutritional value, flavor and insect resistance.

"Yield is the Holy Grail," said Dr. Steven Tanksley, the professor of plant breeding and biometry at Cornell's College of Agriculture and Life Sciences who headed the research. "Right now, we have no yield genes in hand, but in the next five to 10 years we might have genes which would have a tremendous impact on agriculture."

While a commercial payoff may be years away, other scientists said the Cornell report was valuable for its validation of a technique for finding genes through maps of DNA, the material that transmits hereditary patterns.

The advantage of this approach is that one need not know anything about the molecular biology of the gene or the protein it encodes. Most biotechnology works the other way, sequencing the genes responsible for expression of known proteins.

Known as map-based cloning, this technique for isolating and identifying genes lies at the heart of the Human Genome Project, the quest to identify every gene on every human chromosome.

The gene project is being jointly financed by the Department of Energy and the National Institutes of Health, and the U.S. Plant Genome Research Program, a project financed by the Department of Agriculture.

"It's the first example, that I know of, of a significant discovery using map-based cloning," said Dr. Roger Beachy, director of plant biology at the Scripps Research Institute in San Diego.

The gene cloned at Cornell gives plants resistance to the bacterium Pseudomonas syringae, which causes a speck, a disease that results in the loss of leaves and reduced yield and can lead to the death of the tomato plant.

The researchers at the Ithaca, N.Y., school identified the gene by locating it on chromosome 5 of the tomato.